I will not do a real review of this excellent serial as that has already been done by a very capable writer. Just want to make a couple of observations of some cast members. In checking Virginia Horne on IMDb who played the large role of Japanese lady Nabura I was surprised that she was a comediene who had the role of Myrtle Mae in "Harvey" starring James Stewart. She was the lady who made egg and onion sandwiches. Then there were the actors Keye Luke and Benson Fong on opposite sides, Luke playing a Chinese and Fong a Japanese. Both men had played sons in the Charlie Chan movies. Both had also played the same character in the stage versions of "Flower Drum Song" and Fong went on to play the character in the movie version.

Secret Agent X-9 was a popular comic strip character of the 30s and 40s. Two serials of the same name were made by Universal (1937 & 1945) based on the character.This one, released in 1945 starred Lloyd Bridges in the lead role. Bridges was just emerging as a star and was a far better actor than most of the other serial heroes of the day.The story takes place in 1943 on Shadow Island an island of intrigue off the coast of China, which has been allowed to remain neutral by the Japanese. Naturally secret agents from both sides of the war descend upon the island which is governed by self-proclaimed owner Lucky Kamber (Cy Kendall). The chief villain of the piece is the sinister Japanese agent, Nabura (Victoria Horne).A Japanese scientist Hakahima (Benson Fong) accidentally discovers that aviation fuel can be manufactured cheaply by mixing an element called "722" with distilled water. Nabura devises a plan whereby an agent whose face is surgically altered to look like the American scientist who has the formula to "722", will be smuggled into the U.S. to steal it. Lynn Moore (Jan Wiley) an Australian agent (with an American accent) learns of the plan and informs her superiors. The U.S. sends in Secret Agent X-9 (Bridges) to foil the plot. Chinese agent Ah Fong (Keye Luke) becomes X-9's partner.A Japanese submarine is standing by to take the impostor to America. there is also a German ship (in the far east?) under the leadership of Kapitan Graf (Arno Frey) and his assistant Yogel (Gene Stutenroth). A French couple, Hotel owners Papa (Ferdinand Munier) and Mama Pierre (Ann Codee) also figure in the plot. A mysterious figure known only as Solo (Samuel S. Hinds) spends most of the picture playing tiddley winks on Kamber's bar. Double crosses and triple crosses abound as X-9 tries to gain the secret of "722".This serial was blessed with a stellar cast of veteran performers. Bridges made a dashing hero. Keye Luke was an ideal partner. Jan Wiley was a fetching heroine. Victoria Horne, made up to look Japanese, goes through the serial looking like she has her eyes closed. Veteran baddie Cy Kendall is suitably evil as he tries to play both sides against the other. Hinds is basically wasted as Solo. His purpose is eventually made clear but not until the final chapters. Gene Stutenroth (aka Roth) looks more like a train conductor than a German officer. And "B" movie vet Edmund Cobb has a small role as the bartender.Oddly enough, the alliance of the U.S., China and Australia is referred to as the "United Nations". This term pre-dates the actual United Nations by only a few months.All in all this is an excellent WWII spy story. It has excellent production values and has an exciting climax in the final chapter. It is a pity that Universal went out of the serial business in 1946.